The underground station at SDSU is the first of its kind in San Diego. At more than 300 feet long, 55 feet underground and 80 feet wide, the subterranean station is as large as a 30-story building turned on its side. The design features a mezzanine level that spans over the eastbound and westbound tracks, twin elevator banks, escalators and a 24-hour security station. The project used approximately 27,000 cy of concrete.